Process for producing hydrocarbons



July 30, 19 0- I F. E. FREY ET AL 2209,450

PROCESS FOR PRODUCING HYDROCARBONS Filed 001N 19, 1936 FREDERICK E. FREY HAROLD J. HEPP INVENTOR.

BYMM E/M ATTORNEYS.

Patented July 30, 1940 UNITED STATES 2,209,450 PROCESS FOR PRODUCING HYDROCARBONS Frederick E. Frey and Harold J. Hepp, Bartlesville, kla., assignors to Phillips Petroleum Company, a corporation of Delaware Application October 19, 1936, Serial No. 106,482

3 Claims.

This invention relates to the production of paraffin hydrocarbons and parafiinic motor fuels of normal gasoline boiling range from hydrocarbon material of lower boiling temperatures, and more 5 specifically to the reaction of simple olefin and parafiin hydrocarbons to produce especially valuable motor fuels and paraflin hydrocarbons of branched structure. I

An object of this invention is to produce a liquid, motor fuel essentially parafiinic in nature without resorting to olefinic polymer formation and the subsequent hydrogenation of the olefin hydrocarbons.

Another object of this invention is the use of a synthetic conversion stock composed of hydrocarbons of simple and controlled composition to produce a liquid motor fuel having especially desir able characteristics and controlled properties, refiecting the identity of the reactant hydrocarbons selected.

A further object is the production of individ ual paraffin hydrocarbons of purity and identity not attainable from natural products nor as the result of usual operations for hydrocarbon manufacture.

Another object is the production of various branched paraffins of a single species or a mixture of simple composition within a wide range of boiling points or volatilities.

Still another object is the production of valuable paraffinic chemical raw materials, such as neopentane (2,2-dimethylpropane) and neohexane (2,2-dimethylbutane) which may be chlorinated to yield predominantly the relatively noncorrosive primary chlorides.

Further objects of our invention will become apparent as the following discussion proceeds.

A number of methods have been proposed for the production of higher molecular weight hydrocarbons from normally gaseous hydrocarbons such as are found in the residue gases from natural gasoline plants or the distillation and cracking of petroleum.

It has been proposed to convert hydrocarbon gases, consisting essentially of paraflins higher than methane, or consisting of olefins or their mixtures such as are produced by the foregoing methods, by 'heat and pressure into hydrocarbons of higher molecular weight. By such means normally liquid hydrocarbons suitable for motor fuel are produced. Polymerization of olefins directly into larger molecules is thus effected, while paraflins so treated are thermally split into smaller molecules, part of which are olefins, which concurrently polymerize. It has also been proposed to decompose paraflins thermally into olefins at a low reaction pressure, thereby favoring the efficient production of simple olefins, which may subsequently be polymerized by a heat and pressure conversion step. Under particularly drastic temperature conditions, the olefinic, parafiinic and heterocyclic polymers are decomposed and normally liquid hydrocarbons of simple composition, but of aromatic structure, survive by reason of the heat stable character of aromatic hydrocarbons. The milder conversion temperatures which lead to aliphatic liquid hydrocarbons yield products rich in olefins, and sometimes 'paraffins, but of exceedingly complex composition, this partly by reason of the high velocity of concomitant secondary reactions.

Such normally liquid hydrocarbon fuels are ordinarily suitable for use as motor fuel in internal combustion engines but difliculties arise from their use under the exacting conditions encountered in certain types of engines such as the high compression type used in aircraft. Thus olefinic and aromatic fuels often lead to excessive heating and variable performance withmodification in engine design. Moreover, use of unsaturated hydrocarbons in motor fuels may lead to deterioration of antidetonation qualities during storage as well as formation of gum, which causes deposits in fuel systems and on valves. Fuels composed of paralfinic hydrocarbons poscess characteristics such that these difiiculties do not arise. It is well known that paraflins of branched structures possess excellent antidetonating characteristics and comparative freedom from heating tendencies in high compression engines. Parafiins of normal structure, on the other hand, have strong detonating characteristics and are accordingly undesirable. Furthermore, for best performance and safety in use, stringent requirements have been applied in respect to volatility and distillation range for fuels intended for such use. Certain branched parafiins having suitable volatility characteristics can be obtained from uncracked natural gas gasoline and petroleum distillates byahighly specialized fractional distillation but the relative amount of such hydrocarbons is ordinarily not large, some structurally possible and valuable species are absent, and undesirable parafiins sometimes overlap the more valuable in distilling temperatures. This leads to considerable expense in producing in this way branched paraflins meeting both antidetonating and volatility requirements. The production of certain suitable antidetonating parafiins by involved synthetic means has been proposed. For example: 2,2,4-trimethylpentane, an octane, has been prepared from isobutylene, which lends itself to catalytic polymerization into diisobutylene, which is then hydrogenated to produce this octane.

In copending applications hereafter to be referred to there have been described methods for producing motor fuel hydrocarbons predominating in branched parafiins by reacting together olefins and parafiins under heat and pressure with suitable control of olefin concentration during reaction.

Thus in U. S. Patent 2,002,394 issued to Frederick E. Frey on May 21, 1935, covering a Process for converting hydrocarbons it was proposed to add at a plurality of points olefins to a parafiinic hydrocarbon stream under the influence of elevated temperature and pressure to produce a motor fuel predominating in branched pa-rafiins. In the copending. application, Serial Number 12,981, filed March 25, 1936, by Frederick E. Frey relating to a Process for converting hydrocarbons there is proposed a process wherein the exothermic heat of reaction between olefins and parafiinic material assists in controlling the reaction temperature level. Also in the copending application Serial Number 82,954 filed June 1, 1936, by Frederick E. Frey relating to a Process for converting hydrocarbons there is described a process for manufacturing motor fuel from raw hydrocarbons deficient in olefin content.

We have discovered that under suitable conditions of conducting the conversion operation the simple juncture of paraflins with olefins can be efiected, with limited extent of secondary and concomitant reactions, to yield a product of simple molecular composition consisting essentially of such resulting juncture compounds of paraffinic type, and this is a part of our invention.

We have discovered that under such conditions the identity of the parafiins produced reflects the identity of the reactant paraffins and olefins, the thermal conversion being of the nature of a controlled chemical synthesis. It is a part of our invention to react together selected single species of parafiins and olefins or simple mixtures to produce at will individual parafiins and simple mixtures of various desired structures and varying boiling points and molecular weights. It is possible to apply fractional distillation economically to such products to procure desired paraffins in a pure or concentrated state.

According to the present invention a paraflin hydrocarbon in its pure state is maintained at a pressure of 1,000 to 10,000 pounds or more per square inch and is at the same time maintained at a reaction temperature such that decomposition reactions are slight and less than 10 per cent and preferably less than 5 per cent of the parafiin undergoes fracture reactions. Suitable temperatures are found to lie between 750 and 1100 F., and while thus heating under pressure in the range described, the olefin is maintained dispersed in the paraflin in a low concentration, less than 10 weight per cent. The juncture of paraffln with olefin takes place essentially according to the equation unaccompanied by extensive juncture of olefin with olefin by reason of the low concentration of olefin present. The reaction is then interrupted and the paraflins thus formed are separated from the products. An olefin in concentration of less than 10 per cent may be initially introduced into the paraifin and the heating conducted in any conventional manner, such as by passage through a heated tube coil to produce a limited yield of synthetic parafiins. If it is desired to react over 10 per cent bf total olefin, introduction of olefin is made to the reacting mixture during the course of the reaction as olefin is consumed, the addition being made in such a manner that the concentration of unreacted olefin in the reacting mixture is maintained at a desired low level. This may be accomplished by introducing olefin at a plurality of points distributed along a tube coil through which the reacting mixture flows, or an olefin rich paraffin-olefin mixture may be injected into a reaction chamber in which an essentially paraffinic mixture is dispersed and mixed with the reacting mixture while the latter is circulated in the reaction chamber so as to flow the partially reacted mixture repeatedly past the point of dispersal. A simple apparatus for this manner of conversion may include an enlarged reaction chamber into which the paraffin-olefin mixture is injected at a velocity sufficient to effect a dispersal in the reacting mixture and maintain turbulence and an active circulation of the total mixture through a heating zone and past the point of injection. Such means are described in the applications hereto referred to and identified, and other equivalent means will be apparent.

The formation of the desired paraffins in a state of relative purity is favored by particularly high pressures while a low concentration of olefin s maintained, ranging from 1 to 5 per cent, for example, at 4,000 pounds pressure per square inch. Pressures of 2,000 to 3,000 pounds per square inch and more are preferable. At a pressure as low as 1,000 pounds parafiins are synthesized in somewhat less purity but the products are predominantly the juncture compounds of the olefin and paraffin reacted if their production is limited to less than 10 per cent of the total reactants per thermal treatment with correspondingly low olefin content, which in such a case may be below 10 per cent, and better if below 5 per cent. Ethylene undergoes somewhat more eflicient juncture with parafiins than do the higher olefins under such low pressure conditions. As higher concentrations of parafiins are built up the thermodynamic limit for the reaction is approached and the synthetic paraflins undergo decomposition, yielding a product which while rich in isopa-rafiins, acquires a very complex composition. High conversion pressures permit increased formation of desirable products, which may amount to 30 per cent of the reaction mixture at 5,000 to 10,000 pounds per square inch, -before other products outweigh the parafllns resulting from primary juncture of reactant paraffins and olefins. Olefins other than ethylene require somewhat higher pressures under otherwise equivalent conditlons. The extent of conversion which permits the ready purification of desired parafilns from the paraflinic products by fractional distillation is dependent on the matetions are readily determined by trial and typical conditions are set forth in the examples-to ,be presented.

All parafiin hydrocarbons undergo reaction with olefins, for example the juncture of ethylene taking place most readily with the replacement of tertiary hydrogen by ethyl, less readily in replacing secondary hydrogen, and least readily in replacing primary hydrogen. Methane and ethane react at a somewhat slower rate than the higher paraffins under equivalent conditions. Olefins of varying structure and molecular weight undergo reaction with parafiins, the higher reaction pressures, or low extent of conversion per thermal treatment being usually required with increasing number of alkyl substituents attached tothe ethylene molecule, if a product rich in primary olefin-parafin juncture products is desired.

While reactant parafiins and olefins consisting each of a single molecular species are particularly desirable to yield paraflin products of simple composition, it is sometimes desirable to use simple mixtures to obtain a desired result. Thus, ethylene and isobutane react to produce hexanes, but a required or specified motor fuel of somewhat lower volatility and gradually rising distillation curve may be produced by reacting both ethylene and propylene with the isobutane whereby heptanes together with hexanes, both of highly branched structure, may be produced to meet a distillation curve specification of this kind. The olefins may be introduced at separate points or may be mixed prior to the introduction. For economic reasons it is sometimes preferable to use simple mixtures, thus ethylene produced by pyrolysis to serve as a reactant may be associated with more or less of difiicultly reacting ethane when absorption or distillation are used to separate the ethylene from other pyrolysis products.

Similarly 2-2-dimethylbutane. and ,2-methylpentane, both hexanes,'may be reacted together with ethylene to produce a mixture of octanes, which are complex and highly branched, but meeting for motor fuel blending purposes specific volatility and anti-detonating requirements.

The drawing diagrammatically shows one type of apparatus for realizing and effecting the teachings of this invention.

' The process of our invention may be conducted in an apparatus such as is shown in the drawing, which is a diagrammatic side elevation of elements, not drawn to scale, and illustrates one means by which the process may be practiced.

Referring now to the drawing, an essentially pure paraflinic hydrocarbon is introduced through pipe I and compressed to a suitable working or reaction pressure by pump II. This pressure will be between 1,000 and 10,0000 or more pounds per square inch. Having been brought to this pressure the paramnic material passes through con-. duit l2 and is subjected to a reaction temperature in coil [3, suitably housed in a furnace or'heating means l4. Such a reaction temperature will be between 750 and 1,100" F., and will be such that the total thermal decomposition of the paraffin hydrocarbon treated, due to its exposure to said temperature, will be less than 5 per cent by weight for reaction periods which may range from about 1 to about 30 minutes, the most suitable exact conditions being determined by trial. .While under these conditions there is admixed with the paraffin hydrocarbon, in a manner to be. hereinafter described, a small amount of an olefin hydrocarbon, the concentration of the said olefin unreacted at any part of the reaction zone will be maintained at less than per cent by weight of the total hydrocarbons present, and the total amount of olefin introduced, per unit amount of parafin present, will be such that, except at particularly high pressure, not more than 30 per cent by weight of the efliuents from the reaction will consist of synthesized hydrocarbons of higher molecular weight.

The desired low concentration of olefin in the reaction zone may be accomplished in a number of different ways. An olefin hydrocarbon, either in a pure state or somewhat diluted by the material introduced through pipe I0, is introduced through pipe l5 and is compressed by pump It to a suitable pressure and carried by conduit I! to the conduits designated by the reference numerals I8 to 26' inclusive, in which the flow is controlled by valves designated by the reference numerals 21 to 35 inclusive, respectively. Another olefin hydrocarbon, also either ina pure state or somewhat diluted by the material introduced through pipe l0, may be introduced, as will be discussed later, through pipe 36 and compressed by pump 31 to a suitable pressure and carried by conduit 38 to the conduits designated by the reference numerals 39 to 43 inclusive, in which the flow is controlled by the valves designated by the reference numerals 44 to 48 inclusive, respectively, and which conduits lead to the conduits l8, I9, 20, 2| and 22 respectively. Hydrogen may be introduced as will be discussed, through pipe 49, and compressed by pump 50 to a suitable pressure, and passed through the conduit 5| to conduits 52, 53 and 54. The hydrogen is passed through these conduits and is controlled by valves 55, 56

and 51. respectively, and passed to conduits 39,

40 and 4| respectively and thence on through conduits I8, [9 and respectively and thence into the reaction coil I3.

In one mode of operation the valves 44 to 48 inclusive, and the valves 55, 56 and 51 are closed, and valves 21 to 35 inclusive are so controlled that a limited quantity of the olefin, introduced through pipe [5, passes to the reaction through each of them, the total amount of unreacted olefin at any one point not exceeding 10 per cent by weight of the hydrocarbons present at that point. With such a procedure elliuents from the reaction coil I3 will pass through conduit 58 and valves 59 and 60 to the separating means 6| with valve 62 in conduit 63 and the valve 64 in conduit 65, which conduits make connection with the insulated reaction chamber 66, being closed as will be the valve 61 in conduit 68. v The pressure in separating means 6|, which will be somewhat lower than the reaction pressure, is controlled by the valve 60.

Another mode of operation, involving the addition of two olefins separately to the reacting stream, may also be followed. In this procedure, a parafiin hydrocarbon is introduced through line l0, compressed to a suitable pressure in excess of 1,000 pounds per square inch by pump II and passed through conduit I 2 to the reaction coil l3, where it is subjected to a reaction temperature between 750 and l,100 F. An olefin hydrocarbon, either in a pure state, or diluted as discussed previously, is introduced through pipe l5, compressed to' a suitable pressure by pump I6 and led by means of conduit H to the stream of paraffin hydrocarbons, being introduced through conduits 23, 24, 25 and 26, valves 21 to 3| inclusively being closed. The fiow of this olefin into the mixture through pipe 23,24, 25 and 26 is controlled by valves 32, 33, 34 and 35 respectively. Another olefin, either in a pure state or somewhat diluted by the material introduced through pipe I0, is introduced through pipe 36, compressed to a suitable pressure by pump 31 and passed through conduit 38 and into the reacting mixture through conduits 39 to 43 inclusive and conduits l8 to 22 inclusive, valves 21 to 3| inclusive being closed as mentioned, and valves 55, 56 and 51 also being closed. The flow of this second olefin stream is controlled by valves 44 to 48 inclusive respectively. In such a mode of operation the paraflin hydrocarbon introduced through pipe Ill-is reacted first with one olefin to form a higher molecular weight paraffin hydrocarbon as a product and then with another olefin to form a similar higher molecular weight parafin hydrocarbon as a product which, however, contains a different number of carbon atoms per molecule than does the first mentioned product. Efliuents of the reaction coil l3 pass directly to the separator 6| as heretofore described.

Higher molecular weight hydrocarbon material produced in this manner is predominantly composed of relatively few species of paraflinic hydrocarbon molecules, most of which have a more or less highly branched structure. A certain limited amount of olefinic material usually polymerizes with itself, forming a limited amount of higher molecular weight olefins. Although heavier hydrocarbon material recovered as a final product is essentially parafiinic in nature, it may be desirable further to decrease any olefinic molecular species. We have found that hydrogen introduced into the last part of the reaction coil, after paraffin-olefin polymerization reactions have been essentially completed, will react with olefin present, to form the corresponding paraffin hydrocarbons.

This addition to our process may be included in either of the' above two modes of operation.

In either case, when the olefin content is low;

hydrogenation may be practiced as' follows.

Valve 21, in conduit I8 is closed, as is valve 44,-

in conduit 39. Hydrogen is introduced through pipe-49, compressed by pump 50 to a'suitable pressure, and passed by conduit 5| to conduit 52, valves 56 and 51 in conduits 53 and 54 being closed. The flow of hydrogen through the conduit 52 'is controlled by valve 55, and continues through conduit 39 into conduit l8 and into the mixture, reacting with the olefins present in the mixture in the very last part of the coil l3. The total eiiluentsof the coil |3 are passed to separator 6| as has been described.

-In another mode of operation the olefin may be introduced only through, conduit H to conduit l8 and through valve 21, while the remaining valves 28 to 35 inclusive, 44 to 48 inclusive and 55, 56 and 51 are closed. In such a case, the eiiiuents may be introduced turbulently into insulated reaction chamber 66, which is efiected by valve 59 being closed and valve 62 in conduit 63 and valve 64 in conduit 65 being open. Coil |3 serves in this case to impart heat suflicient to sustain reaction in chamber 66 but not prematurely to react the olefin-rich mixture in coil l3 when olefin concentration employed therein exceeds the desired low reaction concentration. All the eflluents from the reaction may pass directly into separating means 6|, or valve 61 in conduit 68 may be partially opened and only a certain portion of the eifluents allowed to pass into separating means 6| through valve 60, the remaining eflluents passing through valve 61 and conduit 68 to the hot oil pump 69 which forces the stream through conduit 16 and valve 1| and into the conduit I2.

The introduction of small amounts of pure olefin material into the reaction to maintain the various conditions desired may be made by any one of these methods or any obvious modifications of them, and any past or future references to such introduction of olefins will be so under: stood. Olefinic hydrocarbons so introduced may be diluted before introduction into the reaction zone with some of the parafi'inic reactant, as discussed, so as to inhibit polymerization of the olefin with itself at the point of introduction when such olefins are introduced into the reaction zone. Thus conduit I5 may introduce into the process a mixture consisting of the pure paraflin hydrocarbon introduced through conduit [0, and the pure olefin to be reacted therewith. Also conduit 36 may introduce into the process a mixture consisting of the pure paraflin hydrocarbons and the pure olefin to be reacted. In such a case the olefin concentration passing through pipes l5 and 36 will be appreciably greater than its respective concentration in the reaction mixture as discussed previously, and the amount of parafiin hydrocarbon thus introduced with the olefin is to be considered when considering the composition of the mixture at any point.

The olefin concentration is purposely kept low, so as to favor reactions involving paraflin-olefin juncture and to inhibit polymerization of one olefin species itself or with another species. Because of the high concentration of paraifinic material throughout the reaction coil, more than one olefin species may be introduced for reaction, such introduction being made separately, without going outside the scopeof this invention. The composition of 'the higher boiling material thus synthesizedwill still be simple, and will consist predominantlybi only a few molecular species. s me h gherm'olecular weight olefinic hydrocarbons may be formed as a side reaction from polymerization of the olefins introduced. When such olefins are present, hydrogen may be added as has been discussed, to produce a more completely paramnic .'product. If such olefins are present inia very' low concentration, such as 2 per cent by weight or less, hydrogen in not too great an excessmay be added at only one point as shown above. With somewhat larger amounts of olefins. present, two or more points of hydrogen addition may' be desirable as provided for in the operation. In such a case, hydrogen added at any but the last point should be in such a quantity as to be insufficient for reaction with all the olefin at the point of introduction. In this manner excessive development of heat and reactions involving splitting of parafiinic molecules will be inhibited. When reaction chamber 66 is used, addition of hydrogen will not be desirable.

In separating means 6| hydrocarbons of high molecular weight wil be removed and discharged through conduit 12 to the separating means 13, wherein any heavier products are separated and discharged through conduit 14 and valve 15. Hy-

drocarbon materials of motor fuel boiling range, consisting predominantly of a limited number of molecular species, and essentially par'aflinic in stature. will pass from separator 13 through conduit 16 to fractionating means 11, wherein isoparamn fractions concentrated as to desired components are separated and discharged through conduits 18, I9, 80.an'd 8i which are controlled by the valves 82, 83, 84 and 85 respectively. The products may then receive any further desired purification treatment. The effluents of the reaction passing into separator 6| andnot being discharged therefrom by conduit 12 will mainly consist of unreacted reactants,

Example! Referring to an apparatus whose essential characteristics may be illustrated by reference to the drawing, propane of better than 99 per cent purity was introduced through conduit l0 and increased to 4,500 pounds per square inch pressure by pump II and led through'conduit l2 to a reaction coil l3 where it was subjected to a reaction temperature of 950 F. A seven to one recycle ratio was used by proper manipulation of valves 60 and 61, the recycle going through conduit 68 to pump 69 and conduit 10 to conduit l2. A small amount of ethyleneof greater than 99 per cent purity was added through conduit l5, pump I6, conduits l1 and 26 and valve 35, no other points of addition being used. The length of the reaction coil l3 and the rate of flow through it was such that the average exposure of the propane to the reaction temperature was about 4.1 minutes, while maintaining a steady concentration of reacting ethylene of 2 per cent. The effluents of 'the process passing to the separator 6| contained 11.2 per cent by weight of gasoline hydrocarbons, with unreacted material in such proportion that by appropriate recycling of this unreacted material an ultimate yield of per cent by weight of gasoline was possible. In 100 parts by weight of hydrocarbons charged there were 8.9 parts of ethylene and 91.1 parts of, propane. The gasoline boiling fraction had the following composition by weight:

Iso-pentane, which has high antidetonating qualities and which constitutes a valuable ingredient of aviation fuels, was present in the pentane fraction to the extent of 77 per cent by weight, or 55.5 per cent of the total gasoline produced, and was isolated in a pure state by fractional distillation.

Example II A procedure essentially identical to that given in Example I was followed, using as reactants pure isobutane as the paraflln and pure ethylene as the olefin. In 100 parts byweight of the hydrocarbons charged there were 12.1 parts of ethylene and 87.9 parts of isobutane. A pressure of 4,500 pounds per square inch was used and a reaction temperature of 940 F. with a total exposure time of about 4 minutes. The products contained 16.1 per cent by weight of gasoline boiling hydrocarbons, with a possible ultimate yield by proper recycling of 89 per cent. The gasoline boiling fraction had the following composition by weight:

The fraction consisting of six carbon atoms was 59.9 per cent of thetotal heavier material formed. This fraction consisted of per cent .of saturated hydrocarbons, of which 78 per cent was 2,2-dimethyl butane, a highly branched paraflin hydrocarbon with very good antidetonating qualities and a good component for aviation fuels. A 2,2-dimethylbutane fraction was isolated readily in a pure state by fractional distillation and had the following properties:

Boiling point 121 F.

Reid vapor pressure .9.5 pounds per square inch Densityat 27 C. 0.642

Gravity at 60 F .85.? A. P. I.

Unsaturates 0.9 per cent Blended with aviation gasoline blending stock of lower volatility, high anti-knock value and high lead responses were observed. In the pure state, the ZZ-dimethylbutane-had an anti-knock value of 95 by the A. S. T. M. method D 35'L34T. This hydrocarbon is particularly suitable as an ingredient of aviation fuel and may be admixed with appropriate gasoline blending stocks, suitably in a proportion exceeding 5 per cent to impart volatility without excessive vapor pressure as well as improved anti-knock rating.

Example III Following aprocedure similarto that given in Example I, pure isobutane was used as .the paraffin and pure isobutylene as the olefin component of the charge stock. In parts by weight'of the hydrocarbons charged there were 10.3 parts of isobutylene and 89.7 parts of isobutane, although as a result of applying the procedure described, only a 4 per cent concentration was maintained in the reaction zone. A pressure of 8,000 pounds per square inch and a reaction temperature of 890 F. was used, with an average the reacted material of about 92 per cent. The

gasoline had the following composition by weight:

Per cent C5 8.7 C6-.. 3.0 C7 j 9.8 Ca B. P. 203-223 F 35.5 Ca B. P. 223-230 F 26.9 Ca B. P. 230257" F 4.5 Above Ca"; 11.6

The fraction containing eight carbon atoms was 66.9 per cent of the total gasoline fraction and was 88 per cent branched octanes, chiefly 2,2,4-trimethylpentane and 2,5-dimethylhexane, both of high anti-knock value and lower volatility than the hexanes of Example II.

Example IV Following the procedure as given in Example I a mixture containing in parts by weight 95.2 parts of isobutane and 4.8 parts of propylene, was compressed to 4,500 pounds per square inch and treated in the reaction zone at 940 F. for a period of 7.3 minutes, the fresh charge being introduced to a stream of circulating hydrocarbon, the reaction products contained 5.2 per cent of gasoline boiling range hydrocarbons by weight, which had the following analysis in parts by weight:

Per cent C5 7.7 Ca i 18.8 C7 46.7 C8 8.6 C9 12.6 Residue L 5.6

The fraction containing seven carbon atoms contained 90 per cent saturated hydrocarbons from which a fraction of highly branched heptanes, with excellent antidetonating characteristics, distilling at to F. was separated.

Example V Following the procedure of Example I, isobutylene and methane react to yield isopentane and 3,3-dimethylpropane.

Example VI Following the procedure of Example I, isopentame and ethylene were reacted together to yield branched heptanes of high anti-knock value.

Example VII A mixture of 3.5 weight per cent of ethylene and 96.5 per cent n-butane was passed through an elongated reaction tube under a pressure of 2,600 pounds per square inch and at atemperature of 910 F. at such a rate that the reaction time was of.2.3 minutes duration. The olefin content of the mixture was low and the introduction of additional olefin to the reacting mixture not practiced, contrary to the preceding examples. The products contained 3.7 per cent by weight of gasoline hydrocarbons and 30 per cent of the ethylene was unreacted. The composition of the gasoline hydrocarbon in per cent by weight was:

A fraction consisting of hexanes, mostly branched, and constituting 65 per cent of the gasoline was isolated by fractional distillation containing 95.5 per cent hexanes associated with 4.5 per cent of hexenes, the hexanes being predominantly 3-methylpentane.

Example VIII Following the procedure of Example I, isobutane and 2-butene react to form a gasoline with a high content of branched paraflin hydrocarbons, and possessing very good antidetonating characteristics. The gasoline contains over 60 per cent of highly branched octanes, of which 2,2,3-trimethylpentane and 2,4-dimethylhexane are predominant members. These octanes are readily separated in high concentrations by fractional distillation, the fractions having a low volatility and high antidetonating characteristics.

Although the above detailed description shows some preferred embodiments of this invention, the invention is not to be construed as being limited by such embodiments, and to the individual reactants described. What is claimed and desired for Letters Patent is as follows:

1. A process for producing 2,2-dimethylbutane in a substantially free state from a mixture of isobutane and ethylene, which comprises subjecting a mixture of isobutane and ethylene under a pressure in excess of 1000 pounds per square inch to a reaction temperature between 750 and 1100 F. for a period of time such that decomcent, maintaining the ethylene concentration during said period of time at less than 10 per cent by weight of the total hydrocarbons present, whereby a reaction of isobutane and ethylene takes place to produce reaction products at least about 40 per cent of which consists essentially of 2,2-dimethylbutane and separating the 2,2- dimethylbutane from the reaction products.

2. A process for producing a premium motor fuel from normally gaseous hydrocarbons and normally liquid hydrocarbons, which comprises subjecting a mixture of isobutane and not more than 10 per cent by weight of ethylene under a pressure in excess of 1000 pounds per square inch to a reaction temperature between 750 and 1100 F. for a period of time such that decomposition of the paraflin hydrocarbons present does not exceed 10 per cent, adding ethylene to said mixture during said reaction time in such a manner that the concentration of unreacted ethylene present in any representative portion of the stream does not exceed 10 per cent by weight of the total hydrocarbons present whereby a reaction of isobutane and ethylene takes place forming hexanes, separating from the thermally treated hydrocarbons a fraction containing motor fuel boiling range hydrocarbons, subjecting said fraction to a fractional distillation and separating 2,2-dimethylbutane in an essentially pure state as at least 40 per cent of said motor Iuel boiling range hydrocarbons; and subsequently blending said 2,2-dimetbylbutane with an aviation gasoline base stock of low volatility in an amoimt exceeding 5 .per cent of the resultant blend.

3. A thermal alkylation process for producing 2,2-dimethylbutane which comprises subjecting a mixture of isobutane and ethylene to a pressure in excess of 1,000 pounds per square inch and to a reaction temperature between 750 and 1100 F. in the absence of a catalyst for a period 7 of time such that decomposition of paraiilns does not exceed 10 per cent, and maintaining the ethylene concentration during the reaction at less than 10 per cent by weight, of the total hydrocarbons present, whereby a reaction of the isobutane and the ethylene takes placeto produce reaction products the predominant individual constituent of which is 2,2-dimethylbutane, and then separating from the reacted mixture the 2,2-dimethylbutane so produced.

HARO D J. HEPP. 

